The Techstream software is available officially from Toyota Tech EU website but it needs payment. There are workarounds for it that still get the job done. So yes, you will be using Official Techstream software from Toyota. Do not download it from any place else. You can download the latest version of Toyota Teachstream from Toyota Tech EU website (GTS Diagnostic Software):
You will require a workaround for it. PM me for details about that. The REAL issue is connecting the car with a computer because Techstream requires an interface/cable and it won't work with the usual Bluetooth dongles. You need Mongoose Cable for it, cheap knockoffs of which are available readily on Aliexpress and DHGate. Mine works fine with 2007 JDM (JDM doesnt use OBDII) but checked with an old model local Corolla and it also worked.
It failed to work on 2013 model local Corolla though. I think 2012 or 2013 onwards, you need box type of interface. Again, available on Aliexpress etc. but not sure if they'd work or not.